Steam heating system



Oct. 16, 934- D. QR'OSTHWQAIT, JR 1,977,303

' STEAM HEATING SYSTEM File d Feb. 3, 1930 3 Sheets-Sheet l Y 2 @WM QLITTLE g5.

Oct. 16, 1934. D. N. cRosTHwAl'T, JR

STEAM HEATING SYSTEM Filed Feb. 3, 1930 s Sheets-Sheet 5 muuimmIllllllll I I'll! Patented Got. 16, 1934 PATENT OFFICE STEAM HEATINGSYSTEM David N. Crosthwait, Jr., Marshalltown, Iowa, assignor to C. A.Dunham Company, Marshalltow'n, Iowa, a corporation of Iowa ApplicationFebruary 3,1930, Serial No. 425,681 7 Claims. (01. 237-12) Thisinvention relates to a new and improved steam heating system, and moreparticularly to an improved method for automatically feeding steam tothe radiators at substantially the rate at which it is condensed.

More specifically the invention contemplates the use of an improvedvalve in the steam supply pipe which is automatically controlled byvariations in the pressure differential existing between the supply anddischarge sides of the radiator or radiators so that steam will besuppliedat substantially the rate at which it is consumed.

This invention is particularly applicable and 15 designed for use with asystem of heating by sub-atmospheric steam, such as is disclosed in thepatent to Dunham No; 1,644,114 granted October 4, 1927, although it willbe apparent, as the disclosure progresses. that the principles of thisinvention are also applicable to a system utilizing steam at atmosphericor super-atmospheric pressures. In this Dunham type of heating system,the steam is circulated to and through the radiators 'or condensingspaces at sub-atmospheric pressures, which pressures are variedaccording to the amount of heat required for maintaining the space to beheated at the desired temperature. Steam traps are provided at thedischarge side of the radiators, and a substantially constant pressuredifierential suilicient to insure the circulation of steam through thesystem is maintained between the supply and discharge mains regardlessof what the absolute pressure of the steam within the radiators may be.Orifice plates are positioned in the several supply conduits in advanceof the respective radiator units for apportioning the flow of steam toeach radiator in accordance with the condensing capacity of theparticular unit.

It will be apparent that in a system such as has just been described,with the steam trap closed and a certain sub-atmospheric pressureestablished. in the return main, if the flow of steam to the radiator isin excess of the condensing requirements thereof, the pressure in theradiator will be raised and consequently the pressure differentialbetween the supply and re-' turn sides of the radiator will be somewhatin creased. On the other hand, if the steam condenses within theradiator more rapidly than it is suppliedxthe pressure in the radiatorwill limp and consequently the pressure differential will decrease.According to the present inven- 'tion thesevariations from anormalpressure differential are utilized to automatically operate a'normal pressure difierential.

control valve in the supply conduit whereby the flow of steam to theradiator, or radiators, will be varied to compensate for this changefrom a Under ordinary circumstances the valve will assume a position ofsubstantial equilibrium whereby the rate of steam flow to the radiatoris just sufficient to satisfy the condensing requirements, the pressurediiferential remaining substantially constant.

The principal object of this invention is to provide a new method forheating by steam, such as briefly described hereinabove and disclosedmore in detail in the specifications which follow.

Another object is to provide an improved method of controlling the flowof steam to a radiating unit in accordance with the variations in thepressure difierential between the inlet and discharge sides of theradiator.

Another object is to provide an improved method for governing the rateof steam supply to a condensing system, which utilizes changes inpressure caused by varying differences between the rate of steam supplyand the rate of condensation to actuate the controlling means.

Another object is to provide in a system such as described hereinabove,means to cut off the steam supply when a predetermined maximumtemperature has been reached in. the space to be heated, and for againpermitting the steam supply to be turned on when the temperature fallsbelow this maximum.

Other objects and advantages of this invention will be more apparentfrom the following detailed description of one approved form ofapparatus capable of carrying out the principles of this invention.

In the accompanying drawings:

Fig. 1 is an elevation showing the principal elements of a preferredform of sub-atmosphericsteam heating system, in which the improvementsof this invention are incorporated.

Fig. 2 is a vertical central section through the improved flow-controlvalve.

Fig. 3 is an end elevation of this valve, looking from the right at Fig.2.

sub-atmospheric steam heating system, the control system is alsoapplicable for use with other types of heating systems, as will behereinafter apparent. This heating system comprises a boiler orgenerator A, from which the steam flows through supply main B and theimproved flow control valve C. The rate of steam supply is. controlledin the portion the space to be heated.

The controlled steam flow in main B passes through risers 1 and inletvalves 2 into the re. spective radiators D. Suitable orifice plates(such as disclosed in the Dunham patent hereinabove referred to) areinterposed in the respective risers 1, preferably between the inletvalves 2 and the radiators for proportioning the steam flow to therespective radiators in accordance with the size or condensing capacitythereof. The steam traps E are adapted to close when the radiators arefilled with steam and prevent 'the escape of steam therefrom. Whencondensate and non-condensible gases accumulate in the radiators, thetraps E will open and permit the condensate and non-condensible gases toflow out orbe drawn out by the lower pressure maintained in the returnside of the heating system. These gases and condensates flow out throughpipes 3 into return main F and thence through the strainer 4 into theaccumulator tank G. In a similar manner, the condensate and gasesaccumulating in the portion Bof the supply main pass out through floatand thermostatic trap 5 into return main F and thence into theaccumulator tank G. The exhausting mechanism H comprises a eparator tank6 and a pump 7, driven by motor 8, to withdraw water from the lowerportin of tank 6 and force it through ejector 9 and thence back into theupper portion of tank 6 together with the gases and condensate which arewithdrawn from accumulator tank G through pipe 10 and check valve 11into the exhauster casing. The gases are vented from separating tank 6through pipe 12 provided with outwardly opening check valve 13. When acertain amount of liquid has accumulated in tank 6, a float controlledmechanism, indicated generally at 14, operates to open a normally closedvalve so that the pump '7 can force a part of the liquid out throughpipe 16 provided with check valve 1'7, and thence through pipes 18, 19and 20 back into the boiler.

The exhausting mechanism H is operated whenever it is necessaryto buildup the pressure difierential between the supply and discharge sides ofthe heating system, or whenever it is necessary to transfer accumulatedcondensate from the accumulator tank G to the separating tank 6. Thecontrol mechanism J comprises a differential pressure controller 21which automatically opens and closes a switch 22 which operates throughstarter 23 to control the motor 8. The differential pressure controller21 comprises a diaphragm subjected on its oppo-. site sides to thepressures existing in the supply and return sides of the heating system.For this purpose control pipes, 24 and 25 extend to surge tanks 26 and2'7 positioned in the horizontal section 28 of an equalizing pipe 29extending between the supply and return sides of the heating system, therelatively high pressure end of pipe 29 being in communication with thesupply main B and the relatively low pressure end extending down to andcommunicating with the accumulator tank G. A check valve 30 ispositioned in the equalizing pipe between the relatively, high pressuresurge chamber 26 am the relatively low pressure surge chamber 27. Thisvalve opens toward the high pressure side of the system and willnormally remain closed unless for some reason a lower pressuretemporarily exists in the supply main than the pressure in the returnmain, whereupon valve 30 will open so as to equalizethe pressures. Thecontrol mechanism J will operate, in a well known manner as describedmore at length in the Dunham patent hereinabove referred to, to causethe exhausting mechanism H to operate whenever the pressure differentialbetween the supply and discharge sides of the heating system falls belowa predetermined minimum and to throw the exhausting mechanism out ofoperation whenever the desired pressure differential has againbeenestablished. Also, a float controlled mechanism in the accumulator tankG (as disclosed in the Dunham patent) acts through switch mechanism 31to start the operation of exhausting mechanism H whenever apredetermined amount of condensate has accumulated in the tank G.

A second equalizing pipe connection 32 extends between the foot ofreturn main F and the boiler return pipe 18, and includes a normallyclosed check valve 33 opening toward the boiler. At such times as it maybe desirable to operate the system at super-atmospheric pressures, or atsub-atmospheric pressures with the exhauster H out of operation, thestop-valve 33 in front of strainer 4 is closed, and the pipe connection32 serves to permit condensate to gravitate to the boiler.

In a shunt pipe connection 13" extending around the control valve Cbetween the portions 3 and B of the supply main, is positioned areducing valve M, of substantially the form disclosed in the Dunhampatent hereinabove referred to. This reducing valve embodies balancedcut-off valves whose movements to closed or opened positions aregoverned by the enclosed pressure diaphragm 34 and the adjust ableweights 35 and 36. The diaphragm 34 is subject on one side to the steampressure in supply main B through a pipe 37 connected at one end to thehousing of the diaphragm and at the other to the supply main at a pointsufficiently remote from the valve M to be uninfiuenced by pressurefluctuations in the vicinity of the valve. This reducing valve M isdistinguished by the fact that the balancing weights 35 and 36 are soproportioned and positioned that a desired sub-atmospheric pressure maybe maintained in the portion B of the supply main, while a somewhathigher pressure may exist in the supply main B leading from the boiler.By properly adjusting the weights 35 and 36 any desired degree of vacuummay be maintained in the portion B of the supply main. Preferably apressure gauge 38 is provided to indicate this vacuum or sub-at-' Imospheric pressure.

It will be noted that gate valves 39 are positioned in the shunt pipeline B"' at either side of reducing valve M, and similarly gate valvesare positioned at either side of the control valve C. Assuming for themoment that the valves 40 are closed and the valves 39 are open, theimproved control valve 0 (hereinafter described) will be out of serviceand the steam pressure will be controlled entirely by the reducing valveM, in which case this system will operate substantially as set forth inthe Dunham Patent No. 1,644,114, hereinabove referred to. Thesub-atmospheric pressure of the steam supplied to the radiators D willbe determined by a proper s ettingof the reducing valve M, and theexhausting mechanism H will be automatically operated whenever necessaryso as to maintain the pressure in the return main F and exhaust side ofthe system lower, by a predetermined difierential, than the pressureestablished in the supply side of the system by the reducing valve M.The radiators D will thus be maintained full of steam at the proper lowpressure for giving the desired heat output.

The improved control valve 0 will now be described, referring to Figs. 2and 3 in addition to Fig. 1. This valve comprises a casing 41 having aninternal web 42 separating the high pressure chamber 43 from therelatively low pressure chamber 44. Inlet port 45 connects therelatively high pressure chamber 43 with the supply main B, and outletport 46 connects low pressure chamber 44 with the controlled portion Bof the supply main. The web 42 is formed with the aligned valve seats4'7 and 48, with which cooperate respectively the connected andsubstantially balanced valves 49 and 50. A removable closure plate 51permits access to the upper portion of the casing 41. The lower portionof casing 41 is closed by a closure plate 52. having an outwardlyprojecting flange 53 secured to the casing by bolts 54, and an upwardlyprojecting flange 55 to center the plate 52 properly within the openingin the lower portion of the casing. The closure plate 52 is formedintegrally with an upward extension 56 of the diaphragm casing member57. This upper dished diaphragm casing member 57 is formed at its loweredge with an outwardly extending flange 58, and a similar lowerdiaphragm casing member 59 is formed on its upper edge with an outwardlyextending flange 60. The two diaphragm casing members 57 and 59 areclamped together at opposite sides of an enclosed flexible diaphragm 62by means of a plurality, of bolts 61 passing through the flanges .58 andand securing these flanges against the opposite faces of the peripheralportion of diaphragm 62. The chamber 63 within lower casing member 59 isopen to the atmosphere through central passage 64. A pipe 65 leads fromchamber 66 in the upper diaphragm casingto a surge chamber 67, whichcommunicates through pipe 68 with the supply main B. The chamber 66 isseparated from the main diaphragm chamber 69 above diaphragm 62 by a'webor baflie .70 designed to prevent the formation of convectioncurrents in the liquid that accumulates above the diaphragm and thusprevent undue heating of the diaphragm 62 from the steam passing throughcasing 41. The upper portion '71 of a lower diaphragm casing issupported from the lower portion- 59 of the upper diaphragm casing bymeans of a plurality of supporting struts 72. The lower member 73 ofthis lower diaphragm casing is clamped to the casing member 71 by aplurality of bolts 74 so as to enclose a second flexible diaphragm 75,similar to the first described diaphragm 62. The chamber 76 abovediaphragm is open to the atmosphere through central passage 77. Thelower diaphragm chamber 78 is connected through pipe 79 with a surgechamber 80 connected through Pipe 81 with return main F. The surgechambers 67 and 80 may be conveniently positioned adjacent one anotherand connected by the supporting member 82, although there is no fluidconnection between these two chambers.

Referring again to Fig. 2, the valve structure comprising the twomovable valves 49 and 50 is provided at its upper end with an adjustablescrew 84 having a lock nut 85 thereon, this screw 84 engaging the coverplate 51 to limit the opening movement of the valves and thus preventundue stresses on the diaphragms 62 and 75. The upper end of a valvestem 86 is threaded in valve structure 83 at 87, and provided with alock nut 88. The valve stem 86 is slidable through a guide 89 in theclosure plate 52 and also passes vertically downward through the centralpassage 90 in web 70. The lower threaded portion 91 of stem 86 passesthrough diaphragm 62 and is sealed thereto by means of the diaphragmplates 92 and 93 held in place by nuts 94 and lock nut 95. The outeredges of the diaphragm plates are preferably curved, as shown at 93', toprevent any cutting action on the diaphragm as it is flexed. The lowerend of the threaded portion 91 of valve stem 86 is screwed into the yoke96 and locked in place by nut 97. A lower valve stem 98 is similarlythreaded into the lower side of yoke 96 and locked in place by nut 99.This valve stem 98 is sealed in the lower diaphragm 75 by means ofdiaphragm plates 100 and 101, and nuts 102 and 103, in the same manneras the upper valve stem is attached to the upper diaphragm. A lever 104is intermediately pivoted at 105 to the lower end of a fulcrum link 106suspended from lug 107 on diaphragm casing member 59. (me end of lever104 is pivoted at 108 in the yoke 96. The other arm of lever 104slidably carries a weight 109 which may be adjusted to difierentpositions lengthwise of the lever arm by fixing a pin 110 in any one ofa series of holes 111 in the lever. It will be apparent that byadjusting the weight 109 outwardly on the lever arm 104, the upwardpressure exerted on the movable valve assembly will be increased. 7

It will be noted that opposed sides of the two connected diaphragms 62and 75 are exposed to atmospheric pressure, whereas the upper side ofthe upper diaphragm 62 is subject to the pressure in the supply side ofthe heating system, whereas the lower side of lower diaphragm 75 issubject to the pressure in the return side of the heating system.Therefore, the net force tending to move the valve assembly downwardlyto close the valves is always equal to the pressure differential betweenthe supply and return sides of the system. It will now be apparent thatwhen this downward force exerted by the pressure diflerential justequals the upward force exerted by the adjustable weight 109, the valveswill be in a state of rest or equilibrium. If the pressure differentialincreases above this fixed normal, there will be a tendency to overcomethe effect of weight 109 and close the valves. On the other hand, if thepressure differential decreases, the Weight l09'will overcome the fluidpressure and further open the valves.

- the tube 131 will a spring In case the valves 49 and Y50 areabsolutelybalanced, that is of equal area, the device will operate as abovedescribed. I In case a semibalanced valve assembly used, the varyingpressure eflect maybe compensated for by employing larger diaphragmplates 100 and-101 on one of the diaphragm's, than the diaphragm plates92 and 93 Jon the other diaphragm. This will change the effective areaof the flexible diaphragms and compensate for the unbalanced areas ofthe two valves 49 and, 50. balanced pressure due to the difference inelevation between diaphragms 62 and 75 may be compensated for by-apropervariation in the relative sizes of diaphragm'plates 92, 93 and lotl,101.

A small bracket 113 from the lowergdi'aphragm casing 73. This motoroperates, through gearing en-, arm 115, theclosed in the casing 114, acrank motor being so controlled, ,ashereinafter de-' scribed, as tomovethe crank jarm 115 through successive arcs of 180 in the. samedirection. The lower end of a stem or connecting rod 116 is pivoted at116' on crank arm 115. Theblock 117 is slidable on the upper portion ofstem 116, and a compression spring 118 surrounding this stem is confinedbetween block 117 and an adjusting nut 119 and lock nut 120. Oppositelyprojecting studs 121 the arms of yoke 122 ,formed on one end of lever123, which is intermediately pivoted at 124 in the lugs 125 projectingdownwardly from diaphragm casing 59. ,The other end 126 of lever 123engages the yoke 96-so that when the outer end 122 of the lever iselevated and theinner end 126 depressed, the valves 49 and 50 will bepositively closed. When the outer am 122 of the lever is loweredand theinner arm 126 is elevated, the yoke 96 will be released so that thevalves will be returned entirely-to the control of the differentialpressure mechanism first described.

The motor. 112 is controlled automatically from thermostat L through thecontrol panel K, so that the control valve C will be closed to entirelyout off the steam supplied to the radia tors when a certain maximumtemperature has been reached in the space where thermostat L ispositioned, and the valve C will again be automatically returned to thecontrol of the differential pressure mechanism when the temperature inthis space to be heated has fallen below the predetermined maximum. Theoperation of this portion of the mechanism will be best understood byreference-to the wiring diagram shown in Fig. 4. The thermostat L, inthe examplehere shown, comprises a member 127 which expands when heatedso as to move arm 128 and through link 129 tip the pivoted yoke 130carrying the tube 131, in which is enclosed a globule of mercury 132. Inthe position shown in Fig. 4, the member 127 is heated and has expandedso as to tip the tube 131 in such a direction that "the globule 132closes a circuit between the contacts 133 and 134 in one end of thetube. At a lower temperature the member 127 will-contract so that betipped in the opposite direction and globule 132 will close a circuitthrough the contacts 135 and 136 in the opposite end of the tube. A wire137 extends from the two central contacts 134 and 135, and wires 138 and139 respectively extend from theend contacts 133 and 136. The threewires 137, 138

' The un-' electric motor l12 'supported by} on block 117 are pivoted inautomatic control switch 140 will be closed.

Red signal light 146 and green signal light 147 are adapted to beilluminated respectively when the thermostat is calling for heat, orwhen no heat is required. The-red and green signal lights 148 andl49qoperate in a similar manner, when the respective-manual controlswitches-;144 and 145 are operated to turn the heat 'ouor cut theheatoff.

-At15 is indicated the automatic circuit controller jorthe valveoperating motor 112. 7 This comprises-a fixed disc carrying a''continuous contactiring'151, a pair of similar arcuate contactrings 152and 153, and a smaller pair of arcuate contacts 154 and 155, the latterarcuate contacts being positioned to overlap the spaces between the endsof contacts 152 and 153. A movable contact arm 156 centrally. pivoted at157 is adapted to rotate in unison with the valve operating crank arm115, in other words, this movable contact member will travel from theposition shown in solid lines (Fig. 4) to the position shown in dottedlines, while crank arm 115 is moving through a corresponding arc of 180.The arm 156 carries connected contacts 158, 159 and 160 adapted toengage respectively with the ring 151, the pair of arcuate contacts.

152 and 153, and the inner pair of arcuate contacts 154 and 155. Theinner pair of arcuate contacts 154 and 155 are connected by a wire 161,and wire 162 leads from contact 145 to the series field 163 of the motorwhose armature is indicated at 112. With the parts in the position shownin Fig.4, the valve is opened, but the thermostat L has just operated inresponse to a maximum temperature to tilt to the left as shownand closea circuit through contacts 133 and 134. A motor operating circuitwillnow be completed as follows: From positive lead 142 through switch 141,wire 164, armature 112, field 163, wire 162, contact 155, wire 161,contact- 154, wire 165, switch 140, wire 137, contact 134, mercuryglobule 132, contact 133, wire 138, switch 140, wire 166, arcuatecontact 152, contact arm 156, circular contact 151, and wire 167 throughswitch 141 to the negative.main 143.

The motor will now commence to operate and will move the crank arm 115and rotate the movable contact arm 156 in a clockwise direction. Beforethe contact 159 has passed off the end of arcuate contact 152, thecontact 160 on the movable arm 156 will have contacted with thearcuatecontact 155. A shorter circuit will now be completed from wire162 through contact 155, movable contact 160, contact arm 156, circularcontact 151, and wire 167 to the negative main. When the movable contactarm 156 has reached the position shown in dotted lines, the contact.160will pass off otthe end of shortarcuate contact 155, thus finallybreaking the motor circuit and the parts will come to rest. The partswill now have been moved so as to positively close the valves 49 and 50and shut ofi the supply of steam to the radiators.

When the temperature in the space to be heated has fallen sufficiently,the thermostat 127 will contract so that the mercury tube will be tiltedin the opposite direction and a circuit completed between contacts 135and 136. A motor operating circuit similar to that first described willnow be completed from contact 136 of the thermostat throughwire 139,switch 140, wire 168, arcuate contact 153, contact arm 156, circularcontact 151 and thence as before to the negative main. This operatingcircuit will be broken when the arm 156 has returned (in a clockwisedirection) to the position shown in solid lines, Fig. 4.

With the valve in the open position, as shown in Fig. 4, acircuitthrough red signal lamp 146 is completed as follows: Frompositive lead 142, through switch 141, wire 169, lamp 146, wire 170,switch 140, wire 166, arcuate contact 152, switch arm 156, circularcontact 151, and lead 167 back to negative main 143. When the valve isclosed and contact arm 156 is in the dotted line position, a similarcircuit will extend from wire 169 through wire 171, lamp 147, wire 172,switch 140, wire 168, arcuate contact 153, con tact arm 156 to thecircular contact 151 and thence back to the negative main. Thus wheneverthe valve is open, the red lamp 146 will be I illuminated, and wheneverthe valve is closed and the system does not require heat the green lamp147 will be illuminated.

In case the automatic control switch is opened, and it is desired toclose the valve manually, the manually operated control switch 144 isclosed, thus completing the first described motor operating circuit fromwire 165 through wire 173, switch 144, and wire 174, to the wire 166leading back to arcuate contact 152. In a similar manner the valves maybe opened by closing the manually operated control switch 145, whichcompletes a motor operating circuit fromwire 165 through wire 175,switch 145 and wire 176 to the wire 168 and thence to the arcuatecontact 153. When switch 144 is closed to cause the open valve to bemoved to closed position, a circuit through red signal lamp 148 will becompleted from positive-main 142 through switch 141, wire 169, lamp 148,wire 177, switch 144,

wire 174, wire 166, arcuate contact 152, movable arm 156, circularcontact 151, and wire 167 to the negative main. This circuit will bebroken and the red light will be extinguished when the arm 156 reachesthe dotted line position and the valve has been closed. In a similarmanner when switch 145 is closed to open the valve, the green light 149will be illuminated by an energizing circuit passing from positive main142 through switch 141, wire 169, wire 178, lamp 149, wire 179, switch145, wire 176, wire 168, arcuate contact 153, contact arm 156, circularcontact 151, and thence through wire 167 to thenegative main. A controland signal system similar to that just described by way of example, isdis closed more in detail and claimed in the copending application ofDunham, Serial No. 396,209, filed Sept. 30, 1929.

'In describing the general operation of this heating system when usingthe improved control valve 0, we will first assume that the gate .valves39 are closed and the gate valves 40 are opened so that the steam supplymust pass through the supply main B and valve C to the portion B of thesupply main from which the steam passes through risers l to therespective radiators D. The desired steam pressure in the boiler isobtained by proper control of the fires beneath the boiler A, or thedanpers or other heat controlling mechanism with which the generator issupplied. The weight 109 is set to respond to a predetermined pressuredifierential between the supply and return sides of the system, and thedifierential controller J should be regulated to maintain substantiallythe same or a somewhat smaller pressure differential. As-

suming that the temperature in the building is below that at whichthermostat L operates to close the valve C, and that the system is notyet filled with steam, the weight 109 will operate by gravityv to openthe valves 49 and 50 to permit a free flow of steam through the valve C.The exhausting mechanism H will now be in operation to lower thepressure in the return main, but this exhausting action will extendthroughout the system, since the traps E are now open. The traps 'willremain open until the radiators D are filled with steam, andduring thistime the exhausting mechanism will be unable to establish any materialpressure differential between the supply and return mains. When thesteam fills the radiators D and reaches the traps E, the traps willautomatically close, after which the exhausting mechanism H will be ableto establish a lower pressure in the return main F than exists in thesupply main B. As this pressure differential reaches the predeterminedvalue, it will act on the diaphragms 62 and 75 to overcome the efiect ofweight 109 and tend to close the valves 49 and 50, thus throttling theflow of steam to the radiators. As the operation of the valve isgradual, the valve in closing will reach a position where the rate ofsteam supply to the radiators is approximately equal to the rate ofsteam consumption or condensation in the radiators, so that thedifferential will remain substantiallyconstant and the valve will tendto remain in a state of rest or equilibrium in that position for feedingsteam to the system at the rate at which it is required. If, for anyreason, the rate of steam supply should exceed the desired rate of heatemission from the radiators, or that rate at which the radiators willcondense steam to compensate for the heat loss from the building, thepressure differential will increase and the valve 0 will tend to close.The condensing rate of the radiators will then exceed the rate at whichsteam is being supplied and the supply pressure will drop so that thedifferential will diminish and the valve C will tend to open again underthe influence of weight 109. It will be apparent that any increase inthe pressure differential will tend. to cause the valve to close and anydecrease in the difierential will tend to cause it to open, and that thegradual action of the valve in opening and closing between its extremelimits of travel will permit it to reach a position of substantialequilibrium that maintains the steam supply substantially equal to thecondensingrate. It will thus be seen that the steam supply will seldom,if ever, be entirely cut ofi and a more building will be maintained.

When this heating system is in properly balanced working adjustment, theheat emitted from the radiators should substantially equal the heat lossfrom the building, which will, of course, vary in accordance withvariations in the outside temperature, being greater when the outsidetemperature is lower and vice versa. Steam should be condensed in theradiators at a constant rate and at a temperature just sulficient toprovide this desired constant heat from the radiators, and the rate ofsteam supconstant temperature in the emission plied through valve 0should be just sulficient to compensate for the rate at which the steamis condensed so as to maintain the radiators filled with steam at therequis'te pressure and temperature. 4

Let us assume, for example, that the system is adjusted so as tomaintain a pressure p in the radiate and the exhausting apparatus H isautomaticallyegulated by controller J to maintain a fixed ,pssuredifferential of, for example, one pound between the supply andreturn sides of the system, that is a pressure pl is maintained in thereturn main F. lit is to be understood that the principal function ofthe exhausting apparatus H is to the return main lower, by asubstantially constant differential, than the pressure in the radiators,no matter what the absolute pressure in the radiators may; be, so thatthe exhausting apparatus, in cooperation with the steam-traps E 'willkeep the radiators purged of condensate maintain this pressure throughvalve C, and

a -5. within the radiators, 5

' radiators and non-condensible gases. Obviously it is necessary tomaintain a lower pressure in the return main than in the radiators sothat the noncondensible gases will be drawn out when the steam trapsopen, and. in order that this pressure difierential may be maintainedwhen the pressure within the radiators is atmospheric orsub-atmospheric, the exhausting mechanism is required to maintain apartial vacuum in the return main. Aside from this function, theexhausting mechanism has no direct control of the steam pressure withinthe radiators, but it does differential substantially constant, andvariations in this pressure differential, as thus established, areutilized to automatically .control the valve C which in turn controlsthe absolute pressure and temperature of the steam within the radiators.

We have assumed that a pressure p has been established within theradiators, steam at this.

pressure and corresponding temperature condensing at a rate justsufficient to maintain the desired heat output from the heating system.Now let us assume that the outside temperature increases, there being aresultant decrease in the heat loss from the building, so that less heatwill be required from the radiators, consequently the condensing ratewill be lowered. Since steam is being supplied at a constant rate thesteam cannot escape from the radiators except through condensation, thesteam pressure willbe temporarily built up for example, to 9+1. At thistime the pressure in the return main is still 10-1, and this increase inthe-pressure differential between' the supply andreturn sides of thesystem will cause the valve C to partially close and cut down the rateof steam supply to the so that the pressure in the radiators will fall,for'example, to p1. The exhausting apparatus will now go into operationto lower the pressure in the return main still further in order tore-establish the pressure-differential necessary to withdrawnon-condensible gases from the radiators. This will tend to cause valve0- to open again and increase the steam supply to the radiators, butthis valve will again .be automatically closed as soon as the steammaintain the-pressure in output from the radiators is just sufficient tomaintain a fixed condensing rate.

on the other hand, assuming an initial pressure of p in the radiatorsand p-l in the return main, let us assume that the outside temperaturefalls so as to increase the heat loss from the building and consequentlyincrease the rate of condensationin the radiators. Since steam is beingsupplied at a constant rate, but is being condensed at an increasedrate, the pressure in the radiators will drop, for example, to p-l. Thevalve C will be automatically opened to increase the steam supply sothat the pressure may be built up, for example, to p+2, assuming that atthis pressure and consequent temperature the condensing rate will beconstant to supply the desired heat emission. The exhausting apparatuswill now permit the pressure in the return to build up to 10-1-1, butwill hold the return pressure at this desired difierential below thesupply pressure so that the radiators may be kept evacuated ofcondensate and non-condensible gases.

All of these pressures may be, and preferably are, subatmospheric, butit will be noted that the automatic operation of the system is dependententirely upon pressure differences, absolute pressures (and consequenttemperatures) .being immaterial to this operation, but these absolutepressures being automatically selected to establish the desired rate ofheat out-.

put from the radiators.

the

If for any reason the temperature inside ,the

open and setting the weights on valve M so that it will only open when asubstantially maximum vacuum has been reached in the heating system.Under all normal operations this valve M will remain closed and thesteam supply to the radiators will be controlled by valve C. However,suppose that thermostat I? has caused motor 112 toclose the valve C thenno steam 'wi11 be supplied to the system. If this condition persists, nosteam being supplied to the system, the traps E will cool off and open,and the'exhauster H will build up a maximum vacuum in the system atwhich time the valve M will automatically open to admit enough steam tothe system to keep the piping warm and prevent the radiators fromchilling off. At the same time the heat emitted will be reduced to aminimum.

While this improved heating system has been here described andillustrated as utilizing only sub-atmospheric pressures, and this formof heating system will give most satisfactory results, it will beapparent that the valve C may be operated in the manner described insystems utilizing steam at atmospheric or super-atmospheric pressures.It is only essentialthat the necessary pressure differential bemaintained between the supply and return sides of the system. If no pumpor exhausting mechanism is used, it will be necessary to maintain asuper-atmospheric pressure in the supply side of the system in order toprovide the necessary pressure differential.

It is to be noted that in the construction of the improved control valveC, no stufling boxes are required. One side of each of the movablediaphragms 62 and is exposed to the atmosphere, whereas the pressurechambers at the other sides of the respective diaphragms will becomefilled with liquid so as to prevent the direct contact of steam with thediaphragms, thus effectively sealing the system against the loss offiuid pressure and prolonging the life. of the diaphragms by protectingthem from the direct action of the gases in the system.

The improved apparatus hereinabove disclosed has been made the subjectmatter of a divisional application filed Februar 4, 1931, Serial No.513,242.

I claim:

1. The method of heating by steam which consists in introducing steaminto a confined condensing space having separate supply and dischargeducts, efiecting the withdrawal from said space of non-condensable gasesand condensate While retaining the steam therein, maintaining a pressurein the discharge duct lower than the pressure in the supply duct by asubstantially constant diiTerence suflicient to keep up circulation andutilizing an increase or decrease in this pressure differential causedby variations in the rate of condensation within the condensing space toautomatically and proportionately decrease or increase respectively therate of steam supply through the supply duct to the condensing space.

2. The method of heating by steam which consists in introducing steaminto a confined condensing space having separate supply and dischargeducts, effecting the withdrawal from said space of non-condensable gasesand condensate while retaining the steam therein, maintaining a pressurein the discharge duct lower than the pressure in the supply duct by asubstantially constant diiference sufiicient to keep up circulation,automatically increasing the rate of steam supply through the supplyduct to the condensing space when this difierential falls below apredetermined standard, and decreasing this rate of steam supply whenthe difierential rises above the standard. 7

3. The method ofheating a space by steam which consists in introducingsteam into a confined condensing space having separate supply anddischarge ducts, eifecting the withdrawal from said space ofnon-condensable gases and condensate while retaining the steam therein,maintaining a pressure in the discharge duct lower than the pressure inthe supply duct by a substantially constant difierence sufiicient tokeep up circulation, automatically increasing the rate of steam supplythrough the supply duct to the condensing space when this differentialfalls below a predetermined standard, decreasing this rate of steamsupply when the difierential rises above the standard and cutting offthe flow of steam to the condensing space when a predeterminedtemperature is attained in the space to be heated.

4. The method of heating by steam which consists in introducing thesteam from a common supply duct into a plurality of confined condensingspaces having a common discharge duct, through restricting orificeswhich limit the amount of steam introduced into each space to thecapacity of such space to condense it, ma taining a pressure in thedischarge duct lower by a predetermined substantially constantdifference than that in the supply duct to eflect movement of fluidsthrough said condensing spaces and withdrawal of non-condensable gasesand condensate, automatically. increasing the rate of steam supplythrough the supply duct to the condensing spaces when this pressuredifferential falls below the predetermined standard, and decreasing thisrate of steam supply when the differential rises above this standard.

5. The method of heating by steam which consists in introducing thesteam from a common supply duct into a plurality of confined condensingspaces having a common discharge duct, through 1 restricting orificeswhich limit the amount of steam introduced into each space to thecapacity of such space to condense it, maintaining a pressure in thedischarge duct lower by a predetermined substantially constantdifference than that in the supply duct to eflect movement of fluidsthrough said condensing spaces and. withdrawal of non-condensable gasesand condensate, varying the pressure of steam in the supply duct to varythe temperature of the steam in said spaces, automatically increasingthe rate of steam supply through the supply duct to the condensingspaces when this pressure differential falls below the predeterminedstandard, and decreasing this rate of steam supply when the difierentialrises above this standard.

6. The method of heating a space by steam which consists in introducingthe steam from a common supply duct into a plurality of confinedcondensing spaces having a common discharge duct, through restrictingorifices which limit the amount of steam introduced into each space tothe capacity of such space to condense it, maintaining a pressure in thedischarge duct lower by a predetemiined substantially constantdifference than that in the supply. duct to effect movement of fluidsthrough said condensing spaces and withdrawal of non-condensable gasesand condensate, varying the pressure of steam in the supply duct to varythe temperature of the steam in said spaces, automatically increasingthe rate of steam supply through the supply duct to the condensingspaces when this pressure differential falls below the predeterminedstandard, and decreasing this rate of steam supply when the diflerentialrises above this standard and cutting oif the flow of ing space when a.predetermined temperature is attained in the space to be heated.

7. The method of heating by steam which consists in introducing steamunder subatmospheric pressure into a confined condensing space havingseparate supply and discharge ducts, effecting the withdrawal from saidspace of noncondensable gases and condensate while retaining the steamtherein, maintaining a pressure in the discharge duct lower than thepressure in the supply duct by a substantially constant difierencesuflicient to keep up circulation, and automatically increasing ordecreasingin response to a decrease or increase respectively in thepressure diiferential the sub-atmospheric 145 pressure maintained withinthe condensing space.

DAVID N. CROSTH'WAIT, JR.

steam to the condens- 130.

